Batteries are commonly used electrical energy sources. A battery contains a negative electrode, typically called the anode, and a positive electrode, typically called the cathode. The anode contains an active material that can be oxidized; the cathode contains or consumes an active material that can be reduced. The anode active material is capable of reducing the cathode active material. In order to prevent direct reaction of the anode material and the cathode material, the anode and the cathode are electrically isolated from each other by a separator.
When a battery is used as an electrical energy source in a device, electrical contact is made to the anode and the cathode, allowing electrons to flow through the device and permitting the respective oxidation and reduction reactions to occur to provide electrical power. An electrolyte, for example, potassium hydroxide, in contact with the anode and the cathode contains ions that flow through the separator between the electrodes to maintain charge balance throughout the battery during discharge.
In some cases, the cathode is formed by coating a cathode mixture directly on a current collector, e.g., a conductive mesh. After coating, the cathode mixture is dried. Drying can cause the cathode to shrink, and in some cases, cause excessive stress in the cathode that lead to undesirable defects, such as cracks, and/or loss of adhesion to the current collector. As a result, this method of making a cathode can limit the loading (the amount of active material that can be formed on the cathode) and the performance of the cathode and the battery in which the cathode is used.